Fluid motor mechanism with reversing means



Nov. 4, 1952 J. A. BLAIR 2,616,401

FLUID MOTOR MECHANISM WITH REVERSING MEANS Filed Sept. 8, 1945 6 Sheets-Sheet l INVENToR. .wm and,

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Nov. 4, 1952 J. A. BLAIR 2,616,401

FLUID MOTOR MECHANISM WITH REVERSING MEANS Filed Sept. 8. 1945 6 Sheets-Sheet 2 /az u2 /Z /j iii C5) INVENToR.

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FLUID MOTOR MECHANISM WITH REVERSING MEANS Filed Sept. 8, 1945 6 Sheets-Sheet 3 e /14 /g /12 A54 4 I U /aa Kirai/v1.' YS:

Nov. 4, 1952 J. A. BLAIR 2,616,401

FLUID MOTOR MEGHANISM WITH REVERSING MEANS Filed Sept. 8 1945 6 Sheets-Sheet 4 @-m lm ww Nov. 4, 1952 J. A. BLAIR 2,616,401

FLUID MOTOR MECHANISM WITH REVERSING MEANS Filed Sept. 8, 1945 6 Sheets-Sheet 5 Wwf/"Hf /34 /56 .fr ,uz

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FLUID MOTOR MECHANISM WITH REVERSING MEANS Filed sept. 8, 1945 e sheets-sheet e bnf/v] Zig-j' :Zazz E .-j-.

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Patented Nov. 4, 1952 FLUID Moron MECHANISM WITH REVERSING MEANS John A. Blair, Pleasant Ridge, Mich., assigner to 'King-Seeley Corporation, Ann Arbor, Mich., a

corporation of Michigan Application September 8, 1945, 'Serial No. 615,219

2 Claims. 1

The present invention relates `to fluid motor mechanisms, `and in particular provides such mechanisms embodying improved means for causing 'the movable elements of themotors to move to and Istop at terminal positions which may be at 'a `desired distance beyond the 'normal operating limits of the motors. An illustrative applicati-on Yof the present motor mechanisms is in connection with automotive windshield wiper systems.

Principal objects of the present invention are to provide fluid motor mechanisms, of the above generally indicated type, which are simple in arrangement, economical of manufacture, and assembly, and which are reliable and eiicient 'in operation: lto provide such constructions of the reciprocati-ng type, employing automatically operated reversing valve mechanism, and further employing parking control valve mechanism, which, generically, serves to reverse the action of the reversing valve mechanism, and establish circuits, through such mechanisms, which cause the motor to immediately move to and stop at a predetermined terminal position; to provide such mechanisms wherein a parking operation of the control valve, made at any time, regardless of the direction of travel of the motor, serves to immediately establish connections through the reversing valve mechanisms which cause the motor to moveto and stop at the predetermined terminal position: to provide such mechanisms wherein in certain embodiments, the control and reversing valve mechanisms are disposed at respectively opposite sides of a valve block, wherein in certain other embodiments the control and reversing valve elements are of telescopically related spool form and wherein vin certain other embodiments the control valve is carried by the reversing valve; and to generally improve and simplify the ccnstruction and arrangement of fluid-motor mechanisms of the above generally indicated types.

With the above as well as other and more detailed objects in view, which appear in the following description and in the appended claims, preferred but illustrative embodiments of the invention are shown in the accompanying drawings, throughout the several views of which corresponding reference characters are usedto designate corresponding parts and in which:

Figure `1 'is a lview inside elevation of a fluid motor embodying the invention;

"Figure 2 is 'a view in 'longitudinal central section, with certain of the parts broken away, yand taken generally along `the line 2 2 of .Figure 3;

Figure 3 Vvis Aa view in transverse vertical section, taken 'along the line 3 3 of Figure 1;

.Figure 4 is a .fragmentary view illustrating a portion .of 'the reversing valve mechanism of Figures 2 and 3;;

i-Fi'guref'is va View, taken along lthefline 5 5 vof Figure 3, 'showing the 'contruction :of vthe control valve;

Figures 6, 7, 8, and 9 are fragmentary sectional views, taken, respectively, along the lines 6 6, 1 1, 3 8, and 9 9, of Figure 3;

Figure 10 -is a diagrammatic view, illustrative of the fluid circuits established under different running `and parking-conditions of the motor;

Figures 1l., 12, 13, and 14 are, respectively, ra series of ydiagrammatic views illustrating additional vmodiiications of the invention, each such View illustrating a different modication; and

Figure 15 is a view taken along the line IE-IE of Figure 13.

It will be appreciated from a complete understanding of the invention that, in a generic sense, the improvements thereof may be embodied in fluid motors of widely diering types and sizes, and particularly designed for widely differing applications. In an illustrative but not in a limiting sense, the improvements are herein disclosed as being embodied in a fluid motor of the double piston type, an example of which is specifically described in Patent No. 2,354,189, granted to Rupert B. Bell, von July25, 1944. 'The illustrated mechanisms are well ladapted for use in connection'with vehicle windshieldwiper systems in, for example, the manner vdescribed in said patent.

Referring to the drawings, the improved motor lii comprises Vgenerally a cylindrical housing or cylinder I2, which is provided with removable end closures I4. Cylinder l2 slidably receives a piston assembly comprisingr a pair of spaced pistons IS, which are rigidly secured as by studs l@ to a connecting rack 20. The motor shaft 22 which is rotatably journaled in bearings 24 and 2li provided therefor in the cylinder l2 has xed thereon as :by a pin '21, Ya gear segment 28 which continuously meshes lwith the rack 25J. Accordingly, reciprocating movements ofthe piston assembly are translated kinto oscillatory or rocking movements of the shaft 22. 'In the illustrated embodiment, the shaft 22 is provided with a crank M, which is adapted for connection to the associated means to 'be operated by the motor.

It will be aopreciated'that the piston movements are effected by applying dierential pressures in 'the chamber spaces I'! and i9 which lie between the piston I G and the corresponding end closures I4, the space between the pistons being continuously vented 'to atmosphere in the illustrated instance. These differential pressures may, of course, be obtained from any suitable source. For example, in utilizing the motor IU to `drive a windshield wiper system, the pressure iferentia'l may be'the difference between atmospheric and subatmospheric pressure obtained in usual fashion by connecting motor Il! through line lll), to the intake manifold of the associated automobile engine.

In accordance with conventional practice, 4motor I0 is provided with snap acting reversing valve mechanism 50, which is automatically actuated at each normal limit of Vtravel of the-piston assembly to reverse the applied fluid pressures and cause the motor to travel in the opposite direction. In addition, the present motor is provided with a manually operable control valve 52, which can be operated at any time, from the running position shown in Figure 1, to a parking position, to cause the motor to move to and stop at a parking position which is at a desired distance beyond a predetermined one of the normal limits of travel. The arrangement is such that if the control valve is moved to the parking position while the motor is moving away from the parking terminal, the motor immediately reverses and travels to the parked position. If the parking valve is moved to parked position at a time While the` motor is moving towards the parking terminal, no change is made in the pressures as applied to the motor and it continues in the same direction until the parking terminal is reached.

Any one of a relatively wide variety of automatic reversing valve mechanisms may be utilized in the practice of the invention, the only requirement being that such valve mechanisms be eiective to accommodate a desired amount of over travel from the normal reversing point to the parked position of the motor. Briefly, the illustrated automatic reversing valve mechanism comprises a hood valve 60, which is slidably received in a, groove 62 provided therefor in the valve block 64, for movement between two spaced operating positions, each corresponding to a particular direction of travel, and which two operating positions are diagrammatically shown in the upper two views in Figure 10. Valve 60 is provided vvith a rearwardly projecting operating post 66, Which is received in a slot provided in a valve actuator or kicker 12 which is pivotally supported upon the valve block 64 by means of a trunnion 14. A leaf spring 16 yieldably holds the trunnion 14 in its bearing and a similar spring 11 holds valve 60 on its seat. Kicker 12 is resiliently connected, by means of a tension spring 18, to a spring carrier 80, which is pivotally connected to the motor cylinder by means of a bearing provided by a stud 82. Carrier 80 is provided with spaced arms 84 which are disposed for engagement by abutments 86 formed on the rack 20 as the piston assembly approaches corresponding normal limits of travel. As will be appreciated, this engagement enables continued piston movement to rock the carrier 80 about its pivot 82, loading spring 18, and ultimately bringing the line of action of spring 18 near, at, or past an over-center position. At approximately the same time, one or the other of arms 84 engages the upper end of kicker 12, enabling continued movement of the spring carrier 80 to positively move the upper end of the kicker 12 and carry spring 18 past the over-center position. As soon as this is accomplished, the loaded spring 18 is enabled to snap valve kicker 12 to an opposite position, during the course of which movement it carries the reversing valve 60 from one of its operating positions to the other. Preferably, the width of slot 10 in kicker 12 is greater than the diameter of pin 66, so that the movement of valve 66 is not initiated until after the spring 18 initiates the snapping movement of kicker 12.

Limits to the movements of the reversing valve 50 are preferably provided by the ends of the valve receiving groove 62, and limits to the snapping movements of the valve 12 are preferably provided by spaced shoulders 88, which arel disposed for engagement by a cushioned bumper on the kicker 12. As soon as the kicker 12 is snapped, as aforesaid, its upper end moves away from that one of the spring carrier arms which actuated it. Consequently, when, under parking conditions, the motor movement is continued past the reversing position, such continued piston movements serve only to continue the rocking movement of the spring carrier 80, and does not require or produce a further movement of the kicker 12.

The parking valve 52 is illustrated as being of the slidable type, anduis being received in a pocket |00, formed therefor in the outer face of the previously mentioned valve block 64. Pocket |00 is provided with a removable cover |02, and a leaf spring |04 is provided to yieldingly bias the control valve into engagement With its seat.

Coming now to the arrangement of pockets in the reversing and control valves, and the arrangements of ports and passages in the valve block 64, the parking valve 52 is provided with a pair of spaced blind pockets I0 and I |2, and with a through passage I4. The reversing valve 60 in turn is provided with a series of three blind pockets H6, ||8, and |20.

Referring particularly to the sectional views of Figures 6, '7, 8, and 9, and to the diagrammatic view of Figure 10, the valve block 64 is provided with a pair of through passages |22 and |24, which open through the control valve seat |26 as well as through the reversing valve seat |28. In addition, valve block 64 is provided with a pair of spaced vertically extending passages |36 and |32, which, as shown in Figure 1, are continuously connected to the previously mentioned suction line 40. Passages |30 and |32 connect, respectively, with lateral passages |34 and |36, which open, respectively, through the reversing lvalve face |28 and the control valve face |26. To provide connections to the respective piston chambers |1 and I9, valve block 54 is provided with lateral passages |40 and |42, which continuously communicate, through short plugged vertical passages |44 and |46, with longitudinally extending passages |48 and |50. Passages |48 and |50 are formed in a boss |5||53 which projects radially from the surface of the motor cylinder I2, and these passages open into the piston chambers I9 and |1, respectively. While the present motor may, of course, be arranged to park at either limit position, the illustrated porting is such that the motor |0- parts at the lefthand limit, a viewed in Figures 2 and 10, which position corresponds to a right-hand position as viewed in Figures 1 and 6 through 9. With this arrangement, chamber I9 is connected to atmos- Iphere when the motor is parked, and consequently cylinder passage |48 may, if desired, be

arranged to open directly into chamber I9 irnmediately adjacent the corresponding end closure I4. On the other hand, in the parked position, chamber |1 is associated with the suction circuit and it is consequently preferred to provide means to close oi such suction line when the left-hand piston reaches the parking position. Accordingly, in accordance with the arrangement described in the copending application of .Emil E. Sivacek, Serial No. 564,829, led November 23, 1944, the .passage |50 is arranged to open into a small auxiliary chamber v|52 which is formed between the two spaced laminations |4a and |419 of the corresponding closure 4. The ,inner lamination 4a is provided with an aperture which receives a grommet |54, having apassage |56 therethrough. When the corresponding.

piston 1'6 reaches the parking position, it :engages and is resiliently brought to rest sby'Jg-romrnet |54. Such engagement 'also closes k-ofE passage |56, causing 'the piston .l `to tbe 'maintained 'at the parking position under the influencent the 'suction inv` :passage |50.

Revertin'g to the description loi the passages in valve block t4, it is furtherprovided with 'a passage |69 `vwhich extends'entirely therethrough from the reversing valve .seat |28 tothe control valve :seat |26. The control valveseat `|26 'is provided with a shallow groove |62, of 'generally U-shape, which extends from passage lffto 'a point |64 which is immediately to the le-ft roi passage |24. The groove |62 is at vallitirnes covered by the :body of the control valve 52, and this groove, therefore, iserves only '5to continuously interconnect passage |1595! 'with what may 'be termed, for present :descriptive purposes, the control valve 'port 1154.V In vthe diagrammatic view, Figure l0, all passages 'through the valve block are :considered 'as :lying 4in substantially the same plane :and consequently, to simplify the drawing, the :groove i 512 4is illustratedas lbeing fformed entirely within the bodylof'th'e block 64.

appears in the upper 'ltwo `views yof Figure 1-0., 'when lthe control valve '5-2 is in the running position, the pocket Hi) "thereof serves to close yori the previously .mentioned 'control port |54; pocket ||'2 bridges and "interconnects passages |35ia`n'd 12s; andthe through passage |`|4 serves to vent passage |22 to the atmosphere. AvIn 'its parking position, on Ythe 'other hand, as appears inFig'urel and in the lower 'two views of Figure 1G, pocket Hb bridges port |64 and passage |24; p'o'clre't ||`2 bridges land interconnects passages |'221an'd TBE, and 'the 'through'passage H24 is inactive. Furtherfas viewed in lFigure "9, and in the 'top vi'ew'fof Figure 1'0, when 'the reversing valve il@ lis in 'aposi'tion 'to 'cause rightward travel of the motor as viewed in lFigures 2 and `10 (or leftward travel lcf 'the motor as viewed in Figures 1 and 6 through 9) ,pocket I'S bridges but closes oi passage 134'; pocket H8 "bridges and interconnects passages 'l22-and |50; pocket |2B'bri'dses and interconnects passages |24 and |48; and passage It!) is exposed to atmosphere. In the opposite position of the reversing valve', however, shown in the second view of Figure 10,

pocket lli `bridges and Vinterconnects passages |34 Sand TBD; pocket H8 'bridges but "closes on passage |22; pocket l|29 bridges and intercon-I nectspa'ssages [-24 rand 15S, and passage ls-sis exposed to atmosphere.

It is believed that the operationo'fthe motor can best be described in tconnection with Figure "in `which vfigure the upper 'two views lshow the suction and atmospheric lcircuits 4for Vthe two positions 'of the reversing valve '60, and for 'the running position of the control valve 52. Referring to fthe top view, motor chamber l1 'is connected to the atmosphere through a circuitwhich includes passages |14 and |22, Vpocket H8, and cylinder passage '|553 into chamber On the other hand, chamber I9 is connected to suction through y'a circuitwhich extends from the .operating suction ,passage 132 through passage |35, control valve pocket 2, ,passage |24, reversing valve .pocket |2il,.and .passage |48 into chamber I9. Under .these conditions, the .piston assembly is caused to move tothe righ-t as viewed in Figures '1., 2, and V10. From previous description, it will be understood that when .thenormal righthand limit of travel is reached, Kas viewedinrthese gures, the reversing. val-ve B0 .is .automatically snapped to 'its opposite position, shown in the second view of Figure 10. Under these :conditions, chamber |.1 is connected to 'suction through a circuit which includes cylinder passage |58. reversing valve Apocket 1120 passage |24, kcontrol Valve pocket H2, and passages |36 and |32 to the suction line. Onthe other hand, chamber I9 is connected directly to atmosphere 'through the new yexposed cylinder passage |48. It will be noticed by .inspection of the upper two views of Figure 10 that any fluid circuits, except the above traced'suctionand atmospheric circuits, are blind or vinactive circuits under the above-,mentioned Operating conditions.

vSo long., therefore, zas the .control vvalve occupies the running Aposi-tion, the piston assembly reciprocates between .normal .left-hand vand righthand positions, determined by the adjustment :of the operating means for the reversing valve .60.

The lower two views of Figure 10 illustrate the parking circuitswhichare established 'when valve Gil is moved from the running position to the parking position, and in both of these lower two views, the resulting circuits are such as to apply suction to the left-hand chamber ITI (Figures 2 and 10) 'and to apply atmospheric pressure to the right-hand chamber I9, thereby lcausing the motorto move to and stop at the parking position, at the left-hand limit of travel. In the third view of Figure 10, 'the reversing 'valve is in a position to cause rightward travel of the motor. The 'circuit for applying suction to chamber I1 extends through passages |59 and |42, `reversing valve pocket H5, passage |22, control valve pocket `I |2,and passages |36 and |32 to the -suction line-4), Under the same conditions .the circuit for admitting atmospheric pressure to chamber i9 extends through passage |48, pocket |20., passage I 24, pocket I il), and passages |62 and |60 to the atmosphere. Accordingly, it will be 4appreciated that if the control valve is moved to the parking :position while the motor is movingA to the right, as viewed in Figures 2--and 1Q, the operating pressures applied to the motor are immediately reversed, causing the motor "to Astop and re-start to the left. When the motor reaches the normal left-hand limit, no operation vof the freversing valve 6@ is produced, since, under these conditionsvalve t@ is already in the position to which it would normally 'be moved by the Yarrival of thernotor at the left-hand limit. Consequently, the motor continues on past Iche left-hand limit and comes to rest-when the Vleft-handpiston It seats over the 'grommets |54, thereby closing ofthepassagezl 56,*all as described above.

The bottom view of ,Figure .l0 illustrates the circuits which obtain in thek event that the ,parkingV valve is moved to parking position when the motor is moving towards the parking position. Under 'these conditions, chamber remains connected tofsuction and 'chamber i9 remainsconnected to atmospheric "pressure, the only circuit change which is produced being a change in the arrangement ci passages through which these chambers are connected respectively to suction and to atmosphere. More particularly, in .the lower view of Figure `1|), chamber I1 is connected to suction through passage IES, pocket |20, passage 12d-pocket -l ID, passages |612 and ISU, pocket H, and passages |34 and :|352 to the suotionline 40. VOn ythe other hand, rchamber I9 remains directlyconnected to atmosphere through passage |48. When the YYmotor'reaches zthe normal leftmatcally thrown .to fthe position fshown :in fthe 7 third lview of Figure 10, which action has no eiect on the suction and atmospheric conditions applied to chambers I'I and I9, since the circuits are now the same as those described in detail in connection with the third view of Figure 10. Accordingly, the motor continues on past the lefthand limit and comes to rest at the parking position at the left-hand limit of travel.

The embodiment of Figure 11 is functionally the same as the above described embodiment of Figures l through l0, but employs a somewhat different arrangement of passages and pockets in the control and reversing valve members 52 and 60. More particularly, in Figure 11, the valve block 64' is provided with through passages |80, |82, and |84 which open through the respective control and reversing valve seats |26' and |28'. In addition, the previously mentioned cylinder passages |48 and |58, open through the reversing valve seat |28'.

The suction line 40 is provided with branches |86 and |88, which open, respectively, through the valve seats |26 and |28'.

In this instance, the control valve is provided with'a pair of blind pockets |99 and |92, and the reversing valve is provided with four pockets |94, |96, |98, and 200, all whereof are blind pockets, except that pocket |98 is continuously connected to atmosphere through a short passage 202.

As indicated by the legends, the upper two views of Figure 11 are running positions, the top View showing the circuits which produce rightward movement of the piston assembly and the second View showing the circuits which produce leftward movement of the piston assembly. The lower two views of Figure 11, on the other hand, show the circuits which obtain when theI control valve 52' is in parking position, and it will be noticed that inboth of these views, line |50 is connected to suction, independently of the position of the reversing valve 69', thereby continuously completing the circuits which cause the motor to move to and stop at the left-hand terminal position.

More particularly, in the top view of Figure 11, the suction chamber II is connected to atmosphere through a circuit which includes line |50, reversing valve pocket |94, and passage |80, to atmosphere. At the same time, chamber I9 is connected to suction through a circuit which extends from the suction line 40, branch passage |86, contro-l valve pocket |90, passage |82, reversing valve pocket |96, and line |48 to chamber I9. In the second view of Figure ll, the suc-- tion circuit for chamber I1 extends from the suction line 40 through branch passage |86, pocket |90, passage |82, reversing valve pocket |96, and line |50 to chamber I1. In the same figure, the atmospheric circuit for chamber I9 extends through line |48, and reversing valve pocket |98 and passage 202 to atmosphere. The suction and atmospheric circuits for chambers |1 and I9 respectively, in the lower two or parking views, are believed to be obvious from the above description.

Except as noted above, the construction and arrangement of the embodiment of Figure 11 may duplicate that of Figures 1 through 10.

The embodiment of Figure 12 is functionally the same as those of Figures 1 through 11, with the exception that in this instance, the automatic reversing valve and manually controlled control valve members, 2 I 0 and 2 I 2, respectively, are telescopically related, and are of spool form. More particularly, vthe automatic reversing valve element 2| 0, of tubular form, is slidably but nonrotatably received Vin a cylindrical bore 2I4 provided in the associated valve block 2I6. Valve element 2|0 is provided with two longitudinally extending diametrically opposite grooves 2I8 and 2 I9; and with two diametrically opposite radially extending passages 220 and 222. Passage 220 interconnects groove 2|8 with the central bore 224 of valve element 2| 0, and passage 222 connects groove 2 I9 to the bore 224. In addition, reversing valve element 2|0 is provided with a radial passage 226, which extends from the bore 224 thereof through to the outer face, at a point which is angularly aligned with, but axially displaced from, the groove 2 I9.

The valve block is provided with a suction passage 40, which continuously communicates with the groove 2I9, and with the indicated chamber passages |48 and |59, both of which open into the bore 2 I4 at points which are angularly aligned with groove 2 I9 and passage 226.

The control valve 2|2 is provided with heads 230 and 232, and with an` intervening radially reduced portion 234, which defines an annular groove in the control valve 2 I 2.

The upper two views show the circuits which are established under running conditions, the control valve 2I2 being in its running position. The lower two views of Figure 12 show the circuits which are established under parking conditions, with the control valve 2 I 2 in its left-hand or parking position.

More particularly, in the top view of Figure 12, chamber I'I is connected to atmosphere through line I 59 and passage 226. Under the same conditions, chamber I9 is connected to suction through a circuit which extends from the suction line 4I), through groove 2I8, passage 220, around the reduced portion 234 of the control valve, passage 222, groovel 2I9, and line |48 to chamber 'I9, In the second View of Figure 12, chamber II 1s connected to suction, through a circuit which extends from the suction line 40, as previously traced to groove 2 I9, and thence through line |50 to chamber I'I. Under these conditions, chamber I9 is connected directly to atmosphere through line |48.

In both of the lower views, as aforesaid, chamber I'I is connected to suction, the circuits being obvious from the above description. Accordingly, movement of control valve 2|2 from the running position to the parking position immediately establishes circuits which cause the piston assembly to move to and stop at the left-hand terminal position.

The spool type construction of Figure 12 will be recognized as being very advantageous in that pressures are equalized around the peripheries of the control and reversing valves, thereby eliminating any tendencies of these valve elements to stick. It will be appreciated that any suitable means may be utilized to couple the reversing valve 2|2 to snap over mechanism of the type described in connection with Figures l through 10, and that any suitable means, indicated as a control knob 236 may be provided to eiTect movements of the control valve 2 I2 between'the indicated running and parking positions, and to yieldably hold it in these positions, so that snap over movements of the reversing valve, during operation, do not influence the position of the control valve. In all respects, other than those noted above, the construction of Figure 12 may and preferably does duplicate the construction of- Figures 1 through 10.

The embodiment of Figures 13 and 15 is functionally the same as the embodiments described above. In this instance, however, the control valve 240 is carried by the automatic reversing valve 242.

In this embodiment, the chamber passages |48 and |50 open through the reversing valve seat 244, which is provided on the valve block 64". The corresponding openings are aligned with each other, in the direction of reciprocating movements of the reversing valve 242, so that in one position, the reversing valve pocket 246 bridges passage |48, and in the other position, it bridges passage |50. In the first-mentioned position, a through passage 248, provided in the reversing valve, is aligned with passage |50 and connects the latter to atmosphere; in the latter position, reversing valve 242 is to the left of passage |48 and so directly exposes it to atmosphere.

As appears by comparison of Figures 13 and 15, the control valve 240 is provided with a single blind pocket 250, which, in the running position. bridges the laterally offset passages 252 and 254 which are provided in the reversing valve 242. Passage 252 opens through the outer face of the reversing valve and also opens into the previously mentioned pocket 246. Passage 252 opens through the outer face of the reversing valve 242, and also opens into a laterally displaced pocket 256, which bridges the suction passage 40 in all positions of the reversing valve.

As before, the upper two views of Figure 13 show the circuits which arelestablished under running conditions, and the lower two views of the same gure show the circuits which are established under parking conditions. More particularly, in the top view, chamber |1 is connected directly to atmosphere through the aligned passages |50 and 248. At the same time, chamber I9 is connected to suction through a circuit which extends from the suction line 40, into reversing valve pocket 256, passage 254, control valve pocket 250, passage 252, pocket 246, and line |48 into chamber |9. In the second view, of Figure 13, chamber I9 is connected directly to atmosphere through passage |48, and chamber |1 is connected to suction through a circuit which extends, as previously traced (for chamber I9), from suction line 40 into pocket 246. From pocket 246, the suction circuit for chamber I1 extends through line |50 into chamber I1.

In the lower two views of Figure 13, chamber |1 is continuously connected to suction, the circuits being believed to be obvious from the above description.

In the above described embodiments, the control valve 240 may, during normal operation, either move with the reversing valve or may normally remain stationary. By way of illustration, it is assumed that it remains stationary, under the influence of control means such as are described in connection with Figure 12. To effect a parking movement, it is moved from the right-hand or running position, to the left-hand or parking position, shown in the lower two views.

The remaining embodiment, shown in Figure 14, corresponds to the embodiment of Figures 13 and 15, with the exception that in this case provision is made for normally causing the parking valve 240' to move with the reversing valve 242. More particularly, the reversing valve 242 is provided with upstanding abutments 260 and 262, between which the control valve 240 is movable, and a compression spring 264 is provided to normally hold control valve 240 in the running position shown in the upper view, in which it continuously engages the abutment 280. In order to move control valve 240 to the parking position, a manually controlled operator 210 is provided, which may be advanced from its righthand or running position to its left-hand or parking position, in which it forcibly holds valve 240 in the parking position.

Although only several specific embodiments of the invention have been described in detail, it will be appreciated that various further modifications in the form, number, and arrangement of the parts may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. In a fluid motor, first and second members movable relative to each other back and forth between normal limits under the influence of a reversibly applied differential between higher and lower fluid pressures, a supply passage adapted for connection to a source of one of said pressures, and valve mechanism for controlling said motor, said valve mechanism including reversing valve means having means defining passage means for connecting said supply passage to said motor and being automatically operable at said limits to reverse said connection, and control valve means operable, at any time regardless of the position of said reversing valve means to establish a connection, through said reversing valve passage means, of said supply passage to said motor which causes a said relative movement toward one of said limits, said reversing and control valve means being telescopically related to each other.

2. In a fluid motor, first and second members movable relative to each other back and forth between normal limits under the influence of a reversibly applied differential between higher and lower uid pressures, a, ysupply passage adapted for connection to a source of one of said pressures, and valve mechanism for controlling said motor, said valve mechanism including reversing valve means having means defining passage means for connecting said supply passage to said motor and vbeing automatically operable at said limits to reverse said connection, and control valve means operable, at any time regardless of the position of said reversing valve means to establish a connection, through said reversing valve passage means, of said supply passage to said motor which causes a said relative movement toward one of said limits, said valve mechanism including a valve seat and one of said valve means being interposed between said seat and the other valve means.

JOI-IN A. BLAIR.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,674,056 Oishei et al. June 19, 1928 1,840,233 Hueber Jan. 5, 1932 2,354,189 Bell July 25, 1944 2,583,348 Utter Jan. 22, 1952 2,593,626 Stoltenberg Apr. 22, 1952 FOREIGN PATENTS Number Country Date 697,976 France Nov. 5, 1930 473,296 Great Britain Oct. 11, 1937 

